Cathode catalyst, cathode material using the same, and reactor using the same

ABSTRACT

A cathode catalyst used for conversion of a carbon dioxide gas by an electrochemical reduction includes at least one first catalyst layer and at least one second catalyst layer disposed on a surface of the at least one first catalyst layer. The at least one second catalyst layer is a porous structure. The at least one first catalyst layer and the at least one second catalyst layer are physically combined with each other, and materials of the at least one first catalyst layer and the at least one second catalyst layer are different. A cathode material and a reactor include the cathode catalyst are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/792,214, filed on Mar. 11, 2013, entitled,“CATHODE CATALYST, CATHODE MATERIAL USING THE SAME, AND REACTOR USINGTHE SAME”, which claims all benefits accruing under 35 U.S.C. § 119 fromChina Patent Application No. 201210517797.3, filed on Dec. 6, 2012, inthe China National Intellectual Property Administration, the contents ofwhich are hereby incorporated by reference.

BACKGROUND 1. Technical Field

The present disclosure relates to a cathode catalyst, a cathodematerial, and a reactor including the same. The cathode catalyst is usedfor a conversion of a CO₂ gas by an electrochemical reduction.

2. Description of Related Art

Carbon dioxide (CO₂) is considered the main anthropogenic cause ofclimate change, such as the greenhouse effect. Converting CO₂ to usefulindustrial chemicals containing carbon or fuels is a proper way forrealizing a sustainable development of energy and environment.

Ways of converting CO₂ include chemical conversion, biochemicalconversion, photochemical reduction, electrochemical reduction, andinorganic transformation. The advantages of electrochemical reduction ofCO₂ include low cost, simple fabrication system, and mild operationcondition.

Efficiency for the electrochemical reduction of CO₂ is affected by theperformance of cathode catalysts. Metal catalyst particles with one kindof metal and alloy catalyst particles are commonly used as the cathodecatalysts. However, these kinds of catalysts have low reaction activity,and a hydrogen evolution occurs during the process of theelectrochemical reduction of CO₂. These disadvantages result a lowconversion efficiency of CO₂.

What is needed, therefore, is to provide cathode catalysts, cathodematerials, and reactors using the same, which have good reactionactivities and can improve CO₂ electrochemical conversion.

BRIEF DESCRIPTION OF THE DRAWING

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale, the emphasis instead being placed upon clearlyillustrating the principles of the present embodiments.

FIG. 1 is a schematic side view of a structure of one embodiment of acathode catalyst.

FIG. 2 is a schematic view of a structure of a second catalyst layer ofthe cathode catalyst.

FIG. 3 is a schematic side view of a structure of another embodiment ofa cathode catalyst.

FIG. 4 is a schematic side view of a structure of one embodiment of acathode material.

FIG. 5 is a flowchart of one embodiment of a method for making thecathode material.

FIG. 6 is a schematic view of a structure of one embodiment of areactor.

FIG. 7 shows a scanning electron microscope image of a tin catalystlayer of a Sn—Cu cathode catalyst.

FIG. 8 is a comparative plot showing volt-ampere characteristic curvesof the Sn—Cu cathode catalyst fabricated in different current densitiesof the electroplating.

FIG. 9 is a comparative plot showing volt-ampere characteristic curvesof the Sn—Cu cathode catalyst fabricated in different time periods ofthe electroplating.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “another,” “an,” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references mean at leastone.

Referring to FIG. 1, one embodiment of a cathode catalyst 10, used for aconversion of a CO₂ gas by an electrochemical reduction, includes afirst catalyst layer 12 and a second catalyst layer 14. The secondcatalyst layer 14 is disposed on a surface of the first catalyst layer12. The second catalyst layer 14 is a porous structure.

The first catalyst layer 12 can be a plate structure having a uniformthickness. The thickness of the first catalyst layer 12 can be in arange from about 100 nanometers to about 200 micrometers. The firstcatalyst layer 12 can be a free standing structure. “Free standing” isan intrinsic structural characteristic of the first catalyst layer 12.The term “free standing” means that the first catalyst layer 12 cansustain the weight of itself when it is hoisted by a portion thereofwithout any significant damage to its structural integrity. The firstcatalyst layer 12 can be continuous. A surface of the continuous firstcatalyst layer 12 is uniform and dense. The first catalyst layer 12 canalso be porous. A porosity of the porous first catalyst layer 12 can bein a range from about 30% to about 90%. In one embodiment, the firstcatalyst layer 12 is continuous.

A material of the first catalyst layer 12 can be a catalytic metal forthe electrochemical reduction of the CO₂ gas. The material of the firstcatalyst layer 12 can be zinc, cadmium, indium, tin, lead, bismuth,palladium, platinum, copper, silver, or gold. In one embodiment, thematerial of the first catalyst layer 12 is copper.

Referring to FIG. 2, the second catalyst layer 14 is the porousstructure having a uniform thickness. A plurality of micropores 142 areuniformly defined on a surface of the second catalyst layer 14. Theplurality of micropores 142 can be through holes or blind holes. In oneembodiment, the plurality of micropores 142 are through holes. Shapes ofthe plurality of micropores 142 can be circular or rectangular.Diameters of the plurality of micropores 142 can be in a range fromabout 10 nanometers to about 10 micrometers. A porosity of the secondcatalyst layer 14 can be in a range from about 40% to about 90%. In oneembodiment, the porosity of the second catalyst layer 14 is in a rangefrom about 60% to about 90%. The porous structure can be formed bypatterning methods. A contact area between the CO₂ gas and the cathodecatalyst 10 can be increased due to the porous structure during theprocess for the electrochemical reduction of the CO₂ gas. Therefore, areaction activity and a stability of the cathode catalyst 10 can beimproved. The thickness of the second catalyst layer 14 can be in arange from about 100 nanometers to about 5 micrometers.

A material of the second catalyst layer 14 also can be a catalytic metalfor electrochemical reduction of the CO₂ gas. In one embodiment, thematerial of the second catalyst layer 14 is different from the materialof the first catalyst layer 12. In one embodiment, the material of thesecond catalyst layer 14 is tin.

The first catalyst layer 12 and the second catalyst layer 14 are tightlycombined with each other. The first catalyst layer 12 and the secondcatalyst layer 14 are physically combined with each other. The term“physically combined” means that the first catalyst layer 12 and thesecond catalyst layer 14 are combined with each other only byinter-atomic forces or intermolecular forces. There is no chemical bondformed between the first catalyst layer 12 and the second catalyst layer14. In other words, the first catalyst layer 12 and the second catalystlayer 14 are not combined with each other in an alloy form. There is agood synergistic effect in the combining interface between the firstcatalyst layer 12 and the second catalyst layer 14 that are physicallycombined. Therefore, a catalytic efficiency of the cathode catalyst 10can be increased and a hydrogen evolution can be effectively suppressedduring the conversion process of electrochemical reduction of the CO₂gas. Accordingly, the conversion efficiency of the CO₂ gas can beincreased.

Referring to FIG. 3, one embodiment of a cathode catalyst 20, used forthe conversion of the CO₂ gas by the electrochemical reduction isprovided. The cathode catalyst 20 is similar to the cathode catalyst 10excepted that the cathode catalyst 20 includes at least one of aplurality of the first catalyst layers 12, a plurality of the secondcatalyst layers 14, and combinations thereof. Adjacent two catalystlayers in the cathode catalyst 20 use different materials. Each catalystlayer is physically combined with adjacent catalyst layer in the cathodecatalyst 20. In one embodiment, the cathode catalyst 20 includes aplurality of first catalyst layers 12 and a plurality of second catalystlayers 14. The plurality of first catalyst layers 12 and the pluralityof second catalyst layers 14 are stacked with each other. In oneembodiment, the plurality of first catalyst layers 12 and the pluralityof second catalyst layers 14 are alternately stacked with each other.Each of the plurality of first catalyst layers 12 contacts and isphysically combined with at least one of the plurality of secondcatalyst layers 14. Each of the plurality of second catalyst layers 14contacts and is physically combined with at least one of the pluralityof first catalyst layers 12. In one embodiment, the plurality of firstcatalyst layers 12 are stacked with each other to form a firstintegrating catalyst layer, the plurality of second catalyst layers 14are stacked with each other to form a second integrating catalyst layer,and the second integrating catalyst layer is disposed on a surface ofthe first integrating catalyst layer to form the cathode catalyst 20.

The cathode catalysts 10 and 20 can be made by various methods as longas at least one catalyst layer is the porous structure, and two adjacentcatalyst layers use different materials and are physically combined witheach other. One embodiment of a method for making the cathode catalyst10 includes the following steps:

S1, preparing an electroplating solution;

S2, selecting a first catalyst plate as an electroplating cathode and asecond catalyst material as an electroplating anode, wherein materialsof the first catalyst plate and the second catalyst material aredifferent;

S3, electroplating the second catalyst material on a surface of thefirst catalyst plate in the electroplating solution to form a plating onthe surface of the first catalyst plate; and

S4, drying the first catalyst plate with the plating to form the cathodecatalyst 10.

In step S1, the electroplating solution can be formed by the followingsub steps:

S11, providing a complex agent and a tartrate;

S12, forming a mixed solution by mixing the complex agent and thetartrate; and

S13, adding a main salt containing an element of the second catalystmaterial to the mixed solution to form the electroplating solution.

In step S11, the complex agent can be a pyrophosphate. In oneembodiment, the complex agent is a water solution of a potassiumpyrophosphate. The tartrate can facilitate a dissolution of theelectroplating anode and stabilize ions of the second catalyst materialdissociated during the electroplating. In one embodiment, the tartrateis potassium sodium tartrate.

A molar ratio of the complex agent to the tartrate can be in a rangefrom about 3:1 to about 20:1. In one embodiment, the molar ratio is in arange from about 5:1 to about 20:1. In one embodiment, the molar ratiois about 8:1.

The method can further include a substep of adding an additive in themixed solution to increase a poling efficiency of the electroplatingcathode, thereby the plating with uniform and delicate crystallinegrains can be formed during the electroplating. An amount of additivecan be in a range from about 0.2 grams per liter (g/L) to about 0.6 g/L.In one embodiment, the additive is gelatin.

In step S12, a surfactant further can be added to the mixed solution.The surfactant can decrease an interfacial tension between theelectroplating cathode, electroplating anode, and the electroplatingsolution. A scattered ability of the electroplating solution on surfacesof the electroplating cathode and electroplating anode thereby can beimproved. In one embodiment, the surfactant is sodium dodecyl benzenesulfonate (SDBS).

The complex agent, tartrate, additive, and surfactant are physicallymixed and dissolved in the mixed solution, with no chemical reactionoccurring between them. The mixed solution is a liquid.

In step S13, the main salt contains the element of the second catalystmaterial. The main salt can dissociate the ions of the second catalystmaterial in the mixed solution. In one embodiment, the main salt is atin salt wherein the tin element is bivalent. The tin salt can be tinchloride (SnCl₂). A molar ratio between the tin salt and the complexagent can be in a range from about 3:1 to about 6:1. In one embodiment,the molar ratio is about 4:1.

In step S1, the electroplating solution is prepared in a temperaturelower than 40 degrees Celsius. In one embodiment, the temperature forpreparing the electroplating solution is in a range from about 5 degreesCelsius to about 15 degrees Celsius.

In step S2, the first catalyst plate can be the first catalyst layer 12or materials of the first catalyst plate and the first catalyst layer 12can be the same. In addition, the second catalyst material is thematerial of the second catalyst layer 14. In one embodiment, the firstcatalyst plate is a copper plate and the second catalyst material ismetallic tin. The metallic tin can be plate shaped or block shaped. Inone embodiment, the metallic tin as the electroplating anode is blockshaped. The first catalyst plate can be a layered structure with a denseand continuous surface. The first catalyst plate can be a net structure.

In step S3, the electroplating is processed under a temperature lowerthan 60 degrees Celsius. In this temperature range, the plating with auniform thickness can be formed and the plating can be tightly andphysically combined with the first catalyst plate.

In step S3, the plating defines a plurality of micropores. The platingis the second catalyst layer 14. The electroplating is processed under aconstant current density. The current density can be in a range fromabout 5 milliamperes per square centimeter (mA/cm²) to about 30 mA/cm².In one embodiment, the current density is in a range from about 10mA/cm² to about 15 mA/cm². A time period for the electroplating can bein a range from about 1 minute to about 50 minutes. In one embodiment,the time period is in a range from about 10 minutes to about 25 minutes.The cathode catalyst 10 formed in the time period and current densityranges exhibits good catalytic activity.

In step S4, the first catalyst plate with the plating thereon can be airdried or heat dried under a low temperature. The first catalyst platewith the plating should avoid being dried or heat treated under a hightemperature. In one embodiment, a temperature for drying is lower than60 degrees Celsius.

Referring to FIG. 4, one embodiment of a cathode material 100 includesthe cathode catalyst 10 and a conductive support layer 30. The cathodecatalyst 10 is disposed on a surface of the conductive support layer 30.

The conductive support layer 30 can be a porous layered structure. Theporous layered structure defines a plurality of through holes. Theconductive support layer 30 has a certain thickness, which gives thecathode material 100 a three-dimensional structure. The thickness of theconductive support layer 30 can be in a range from about 2 millimetersto about 30 millimeters. In one embodiment, the thickness of theconductive support layer 30 is in a range from about 2.1 millimeters toabout 20 millimeters. The proton transfer rate and an electron transferrate during the electrochemical reduction of the CO₂ gas can beincreased for the conductive support layer 30 with a certain thickness.In one embodiment, the through holes are all curvy cylinders to increasecontact areas between the cathode catalyst 10 and reactants. A materialof the conductive support layer 30 can be a metal or alloy resistant tocorrosion, such as titanium or stainless steel.

In one embodiment, the cathode material 100 is a free standing structureconsisting of the cathode catalyst 10 or 20.

Referring to FIG. 5, for the free standing cathode catalyst 10 or 20,the cathode material 100 can be made by the above method.

Referring to FIG. 6, one embodiment of a reactor 200, used for theconversion of the CO₂ gas by the electrochemical reduction, includes apower source 102, a cavity 104, a solid electrolyte separator 106, acathode 108, and an anode 110. The solid electrolyte separator 106 isdisposed in the cavity 104. The cavity 104 is divided into two chambersby the solid electrolyte separator 106 which are defined as a cathodechamber 112 and an anode chamber 114. The cathode 108 is disposed in thecathode chamber 112. The anode 110 is disposed in the anode chamber 114.The cathode 108 and the anode 110 are separated by the solid electrolyteseparator 108. The power source 102 is disposed outside the cavity 104.The power source 102 has a positive electrode and a negative electrode.The positive electrode of the power source 102 is electrically connectedwith the cathode 108, and the negative electrode is electricallyconnected with the anode 110. The cathode 108 includes the cathodematerial 100.

The power source 102 is used to provide an electrolytic voltage for theelectrochemical reduction of the CO₂ gas. Wind energy, photovoltaicenergy, or electrochemical energy can be used as the power source 102.

The cathode 108, solid electrolyte separator 106, and the anode 110 arestacked in order. The solid electrolyte separator 106 can be an enhancedcation exchange membrane, such as an enhanced perfluoro sulfonatemembrane, enhanced perfluorocarboxylic acid membrane, or a compositemembrane thereof.

The cathode 108 includes the cathode material 100. In one embodiment,the cathode 108 is the cathode material 100 consisting of the cathodecatalyst 10. The first catalyst layer 12 is disposed between the secondcatalyst layer 14 and the solid electrolyte separator 106.

The cathode chamber 112 further includes a cathode inlet 1122 and acathode outlet 1124. The cathode inlet 1122 is disposed at a bottom ofthe cavity 102. A cathode electrolyte and the CO₂ gas are concurrentlyfed from the cathode inlet 1122 and undergo an electrochemicallyreducing reaction in the cathode chamber 112 to form cathode reactionproducts. The cathode reaction products are flowed out along with therest of the cathode electrolyte from the cathode outlet 1124.

In one embodiment, the anode 110 is a porous diffusion electrodeincluding a porous diffusion layer and an anode catalyst layer disposedon a surface of the porous diffusion layer. The anode catalyst layer isdisposed between the porous diffusion layer and the solid electrolyteseparator 106.

The anode chamber 114 further includes an anode inlet 1142 and an anodeoutlet 1144. The anode inlet 1142 is disposed at a bottom of the anodechamber 114. An anode electrolyte and anode active materials can be fedfrom the anode inlet 1142 and undergo an electrochemical oxidationreaction to form anode reaction products. The anode reaction productsare flowed out along with the rest of the anode electrolyte from theanode outlet 1144.

One embodiment of a method for electrochemically converting the CO₂ gasincludes the following steps:

B1, feeding the CO₂ gas into the reactor 200; and

B2, applying the electrolytic voltage between the cathode 108 and theanode 110 to decompose the CO₂ gas.

The step B1 further includes steps of feeding the cathode electrolyteand the CO₂ gas into the cathode chamber 112 and flowing through thecathode 108 and at the same time, continuously feeding the anodeelectrolyte and the anode active material into the anode chamber 114.

The cathode electrolyte includes a first solvent and a first solutedissolved in the first solvent. The first solute can be at least one ofan alkali metal bicarbonate, alkali metal formate, ammonium bicarbonate,and ammonium formate. The alkali metal bicarbonate can be at least oneof sodium bicarbonate, potassium bicarbonate, and a hydrate thereof. Thealkali metal formate can be at least one of sodium formate, potassiumformate, and a hydrate thereof. The first solvent can be water. In oneembodiment, the cathode electrolyte is potassium bicarbonate watersolution.

The anode electrolyte includes a second solvent and a second solutedissolved in the second solvent. The second solvent can be water. Thesecond solute can be an alkali metal hydroxide, alkali salt, ammoniumsalt, or an acid. In one embodiment, the second solute can be sodiumhydroxide, sodium sulfate, ammonium sulfate, or sulfuric acid. The anodeactive material can be the same as the second solute.

In step B2, the electrolytic voltage can be in a range from about 2 V toabout 5 V. In one embodiment, the electrolytic voltage is in a rangefrom about 2.8 V to about 3.5 V. After the electrolytic voltage isapplied, an electrochemical oxidation reaction is continuouslyconducted, and an electrochemical reduction is continuously conducted todecompose the CO2 gas to form expected products. The expected productscan be useful organic substances.

EXAMPLE

Preparation of the Cathode Catalyst 10

Step 1: preparation of the electroplating solution is provided. About0.4 mol of the potassium pyrophosphate is dissolved in about 800 ml ofdeionized water, stirred and ultrasonically vibrated for about half anhour to form a water solution of the potassium pyrophosphate. About 0.05mol of potassium sodium tartrate, about 0.5 g of gelatin, and about 0.1g of SDBS are dissolved in the water solution of the potassiumpyrophosphate to form the mixed solution. About 0.1 mol of SnCl₂ isadded to the mixed solution at about 25 degrees Celsius, stirred andultrasonically vibrated until the SnCl2 is totally dissolved in themixed solution to form the electroplating solution.

Step 2: electroplating process. A smooth copper foil of about 20micrometers thickness and about 99.9% of purity is decontaminated in anacetone and activated in a diluted hydrochloric acid. A tin ingot as theelectroplating anode and the copper foil as the electroplating cathodeare electroplated in a constant current density to form a plated copperfoil. The plated copper foil is washed by the deionized water and driedin an oven at a temperature of about 60 degrees Celsius to achieve aSn—Cu cathode catalyst. A porous tin layer is physically disposed on asurface of the copper foil. Referring to FIG. 7, holes are uniformlydistributed in the tin layer.

Cathode catalysts under different electroplating current densities andelectroplating time periods are provided below. These cathode catalystsare directly used as the cathodes for converting the CO₂ gas by theelectrochemical reduction (without the conductive support layer). Theperformance of the cathodes for the converting the CO₂ gas by theelectrochemical reduction are tested.

Referring to FIG. 8, four samples of the Sn—Cu cathode catalysts a₁, a₂,a₃, and a₄ are prepared under different electroplating current densitiesto be used as Sn—Cu cathodes. The sample a₀ is the copper foil withoutany electroplating. Referring to table 1, five cathodes fabricated bythe samples are tested using a cyclic voltammetry method to testactivities and stabilities thereof. A test result shows that the Sn—Cucathodes fabricated under the electroplating current densities of about10 mA/cm² and 15 mA/cm² have good activities and stabilities forconversion the CO₂ gas by the electrochemical reduction. Especially, theSn—Cu cathode fabricated under the electroplating current density ofabout 15 mA/cm² has the best catalytic activity and stability.

TABLE 1 current density time period for electroplating samples (mA/cm²)(minute) a₀ 0 0 a₁ 5 10 a₂ 10 10 a₃ 15 10 a₄ 20 10

Referring to FIG. 9, Sn—Cu cathodes fabricated under a constant currentdensity of about 5 mA/cm2 and in different time periods of theelectroplating are further tested. The result shows that the Sn—Cucathode has good catalytic activity and stability when theelectroplating lasts for about 20 minutes.

In addition, the Sn—Cu cathode catalysts 10 directly as cathode areapplied in the reactor 200 to convert the CO₂ gas by electrochemicalreduction. A test result shows that a current efficiency of the reactor200 reaches 90% and a conversion efficiency of the CO₂ gas reaches 92%.

Comparative Example 1

A Sn—Cu alloy layer as a first comparative cathode catalyst, in which aSn metal layer and a Cu metal layer are chemically combined as a way ofalloy, is provided. A first comparative reactor using the Sn—Cu alloylayer is used to convert the CO2 gas by the electrochemical reduction.The first comparative reactor is similar to the reactor 200 except thatthe cathode catalyst is different. In addition, conversion conditions ofthe first comparative reactor and the reactor 200 are the same. A testresult shows that a current efficiency of the first comparative reactoris about 80% and a conversion efficiency of the CO₂ gas is about 80%.

Comparative Example 2

Comparative Example 2 is similar to the Comparative Example 1 exceptthat Sn—Cu alloy particles are used as a second comparative cathodecatalyst for a second comparative reactor. A test result shows that acurrent efficiency of the second comparative reactor is about 82% nd aconversion efficiency of the CO₂ gas is about 85%.

Depending on the embodiment, certain steps of methods described may beremoved, others may be added, and the sequence of steps may be altered.It is also to be understood that the description and the claims drawn toa method may include some indication in reference to certain steps.However, the indication used is only to be viewed for identificationpurposes and not as a suggestion as to an order for the steps.

Finally, it is to be understood that the above-described embodiments areintended to illustrate rather than limit the present disclosure.Variations may be made to the embodiments without departing from thespirit of the present disclosure as claimed. Elements associated withany of the above embodiments are envisioned to be associated with anyother embodiments. The above-described embodiments illustrate the scopeof the present disclosure but do not restrict the scope of the presentdisclosure.

What is claimed is:
 1. A reactor adapted for conversion of a carbondioxide gas by an electrochemical reduction, the reactor comprising: acavity; a solid electrolyte separator disposed in the cavity anddividing the cavity into a cathode chamber and an anode chamber; ananode disposed in the anode chamber; and a cathode comprising a cathodecatalyst and disposed in the cathode chamber, the cathode catalystcomprising: a plurality of first catalyst layers; and a plurality ofsecond catalyst layers being porous, wherein a material of the pluralityof first catalyst layers is different from a material of the pluralityof second catalyst layers; the material of the plurality of firstcatalyst layers is selected from the group consisting of zinc, cadmium,indium, tin, lead, bismuth, palladium, platinum, copper, silver, andgold; and the plurality of first catalyst layers and the plurality ofsecond catalyst layers are alternately stacked on each other.
 2. Thereactor of claim 1, wherein the anode is a porous diffusion electrodecomprising a porous diffusion layer and an anode catalyst layer disposedon a surface of the porous diffusion layer.
 3. The reactor of claim 1,wherein a porosity rate of the plurality of second catalyst layers is ina range from approximately 40% to approximately 90%.
 4. The reactor ofclaim 1, wherein a plurality of micropores are defined in the pluralityof second catalyst layers, and diameters of the plurality of microporesare in a range from approximately 10 nanometers to approximately 10micrometers.
 5. The reactor of claim 1, wherein thicknesses of theplurality of first catalyst layers are in a range from approximately 100nanometers to approximately 200 micrometers.
 6. The reactor of claim 1,wherein the material of the plurality of second catalyst layers isselected from the group consisting of zinc, cadmium, indium, tin, lead,bismuth, palladium, platinum, copper, silver, and gold.
 7. The reactorof claim 1, wherein each of the plurality of first catalyst layers is acopper foil, and the material of the plurality of second catalyst layersis tin.
 8. The reactor of claim 1, wherein the cathode catalyst consistsof a plurality of copper foils and a plurality of tin layers.
 9. Thereactor of claim 1, wherein each of the plurality of first catalystlayers is a single integral and continuous gapless copper foil.
 10. Areactor adapted for conversion of a carbon dioxide gas by anelectrochemical reduction, the reactor comprising: a cavity; a solidelectrolyte separator disposed in the cavity and dividing the cavityinto a cathode chamber and an anode chamber; an anode disposed in theanode chamber; and a cathode comprising a cathode catalyst and disposedin the cathode chamber, the cathode catalyst comprising: a plurality offirst catalyst layers; and a plurality of second catalyst layers,wherein a material of the plurality of first catalyst layers isdifferent from a material of the plurality of second catalyst layers.11. The reactor of claim 10, wherein the plurality of first catalystlayers and the plurality of second catalyst layers are alternatelystacked on each other.
 12. The reactor of claim 10, wherein a porosityrate of the plurality of second catalyst layers is in a range fromapproximately 40% to approximately 90%.
 13. The reactor of claim 10,wherein a plurality of micropores are defined in the plurality of secondcatalyst layers, and diameters of the plurality of micropores are in arange from approximately 10 nanometers to approximately 10 micrometers.14. The reactor of claim 10, wherein the material of the plurality offirst catalyst layers is selected from the group consisting of zinc,cadmium, indium, tin, lead, bismuth, palladium, platinum, copper,silver, and gold.
 15. The reactor of claim 10, wherein the material ofthe plurality of second catalyst layers is selected from the groupconsisting of zinc, cadmium, indium, tin, lead, bismuth, palladium,platinum, copper, silver, and gold.
 16. The reactor of claim 10, whereineach of the plurality of first catalyst layers is a copper foil, and thematerial of the plurality of second catalyst layers is tin.
 17. Thereactor of claim 10, wherein the cathode catalyst consists of aplurality of copper foils and a plurality of tin layers.
 18. The reactorof claim 10, wherein each of the plurality of first catalyst layers is asingle integral and continuous gapless copper foil.
 19. A reactoradapted for conversion of a carbon dioxide gas by an electrochemicalreduction, the reactor comprising: a cavity; a solid electrolyteseparator disposed in the cavity and dividing the cavity into a cathodechamber and an anode chamber; an anode disposed in the anode chamber;and a cathode comprising a cathode catalyst and disposed in the cathodechamber, the cathode catalyst comprising: a plurality of copper foils;and a plurality of tin layers being porous.
 20. The reactor of claim 19,wherein the plurality of copper foils and the plurality of tin layersare alternately stacked on each other.